1. Field of the Invention
The invention relates to data reading from a smart card.
2. Discussion of Prior Art
A smart card, otherwise known as an integrated circuit card, is a card carrying a microprocessor, memory, and an interface for electrical coupling to read/write devices. Preferably the memory is non-volatile, by which is meant memory which retains information in the absence of electrical power. Typically, memories used in smart cards are of the Electronic Erasable Programmable Read Only Memory (EEPROM) type. Such cards may be used for many purposes, such as for carrying personal information, perhaps for example medical information or for personal identification purposes. Alternatively, such cards may be used as bank cards or payment cards. An application for smart cards to which the present invention is particularly, but not exclusively, applicable is as electronic purses. Electronic purses hold value data which may be uploaded and downloaded by communication with a bank or other financial institution. Value may be exchanged between electronic purses which are coupled by a data link. Thus purchases may be made, using the value data as "electronic cash". Smart cards can carry an appreciable amount of information in a secure manner. Data in the card may include fixed data set at manufacture, such as a card serial number or the like. However this fixed data is not of interest to users. The card is used to input, store and output variable data. Although some of this data may in practice not be changed after first being input, it is different from data fixed by the manufacturer of the card and is use-variable data. More usually, use-variable data is data changed regularly in the normal use of the card. Smart card use-variable data is read to and from the card serially via the contacts using an established protocol.
The read protocol as exemplified in ISO protocol 7816 which requires that when coupling is established between a reader and the card, the reader applies power and clock and reset signals to the card microprocessor. Then, an Answer to Reset (ATR) sequence of data bytes is transmitted from card to reader. Thereafter the card may be interrogated by the reader to transmit demanded use-variable data.
This requires a reader of relative sophistication and expense.
There is a requirement for an inexpensive reader to allow display or use of selected use-variable data from the card. The use-variable data to be read will vary from application to application. In a medical or diary card it may be the details of a next appointment; in a security card it may be a security code to gain access via a lock-release reader; and in an electronic purse it may be the value of the balance remaining. The present invention seeks to provide a system which allows the provision of an inexpensive smart card reader.